CO2 Fixed in Bauxite – Alcoa’s CO2 Capture Process in Australia

Developed in Australia by Alcoa’s Technology Delivery Group, the process works by mixing carbon dioxide into the bauxite residue from aluminium production – forming stable inorganic minerals and ‘locking in’ CO2 that would otherwise be emitted to the atmosphere.

The long-term plan is to deploy the carbon capture technology at Alcoa’s other refineries around the world – in the Australian refineries alone, this could permanently store as much as 300,000 tonnes of CO2 a year.

Although this first-of-a-kind plant has used offsite emissions, Alcoa expect most of their other carbon capture plants will use CO2 from on-site powerhouse emissions.

The Kwinana carbon capture plant was built in 2000 and initially operated as a trial facility. For the last two years, it has carbonated around 25% of the Kwinana refinery’s residue output. Construction of a CO2 pipeline in 2007 has allowed throughput to be increased to 80% of the refinery’s residue output with plans to increase it further to 95%.

The Kwinana carbon capture plant was built in 2000 and initially operated as a trial facility. For the last two years, it has carbonated around 25% of the Kwinana refinery’s residue output.

Residue management is a key sustainability issue for the aluminium industry because of residue volumes and long-term storage requirements.

Up to two tonnes of bauxite residue are generated for every tonne of alumina produced.

The residue is a mixture of minerals that are left behind when the alumina is removed from the bauxite. Mixing concentrated CO2 into the residue reduces its pH level from 13.5 to 10.5. At this level of alkalinity, the residue presents a significantly lower environmental risk and has the potential to be re-used as a value-added resource, for example in road base, building materials or soil amendments.

This is indeed exciting, folks. What makes it even more interesting is that it is not just theory but things are happening on the ground.